The invention relates to an automatic stitch pitch adjuster for a sewing machine. More particularly, the invention relates to a method and apparatus for automatically adjusting the stitch pitch of a sewing machine in situations where the end of the workpiece is not in a normal line but rather may be slanted against the direction of feeding.
As an example of an automatic stitch pitch adjusting device, Japanese patent publication No. 53-38646 is known. In this reference, the predetermined total stitch line consists of multiple stitching with a predetermined stitch pitch and multiple stitching with an adjusted stitch pitch, the adjusted stitch pitch being shorter than the predetermined stitch pitch.
In the known prior art, since the adjusted stitch pitch was predetermined, it was impossible to terminate the last stitch point at a predetermined point unless the first stitch position is positioned at a predetermined point. Further, since the elasticity of a workpiece may not always be constant, then the margin distance may not be kept constant.
Objects of the invention, therefore, include providing a method and apparatus for a sewing machine for terminating the last stitch point at a predetermined position regardless of the first stitch position and providing a method and apparatus for stitching along the end of a workpiece keeping the margin distance constant.